Still in the process of scanning all the albums, scrapbooks and loose photos my parents have collected in their 70 plus years, I'll tell ya that fiddling with the photos on the bed so Photoshop Elements 5 could recognize the gaps (and you must leave decent gaps) so it can separate the pictures out of a scan bed full was too much hassle. Not enough contrast on the edges of photos, like those with light skies, made this an impossible job for Elements to handle.
My HP 6210 all-in-one printer/fax/copier/scanner helps me sit and scan as many as two hundred photos in a day (long day though), a scan bed full at a time without restarting the software. It'll stay open for me to continue adding more pictures and when I finish the batch on the glass, I just hit new scan and repeat selecting each photo by double clicking in the center of the photo usually or use the box to narrow down to one photo like using a crop tool and move that box to the next photo when done capturing it. When done with a batch, the software will save them all in a format I choose in a numbered sequence. Even if you run some software that causes a crash while scanning, the files scanned in the middle of a batch are in a temp folder in bmp format to recover manually. Worked great for the over 4,000 photos I've scanned so far. Next come slides and 8mm films... Thank goodness for audio books as they keep me from getting bored while my hands do the loading, unloading and pushing buttons.